Question

Suppose you plan to conduct a survey to find the average age of unemployed workers. Let's say you decide on the 95% confidence level and state that the estimated mean must be within 2 years of the population mean. If, for planning purposes, you assume a population standard deviation of 10 years, how many unemployed workers should be interviewed to meet your requirements?

Answer 1

Solution

standard deviation =   =10

Margin of error = E = 2

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025 = 1.96

sample size = n = [Z/2* / E] 2

n = ( 1.96*10 / 2 )2

n =96.04

Sample size = n =97